Polar CS100 average speed does not seem accurate

Ally83

Hi

I bought a polar cs100 computer and have been using it for a month now my average speed says 15mph or there abouts. I also use imapmyride on my iphone so that I can record the route on a map and noticed my average speed is about 23mph. So i decided to work it out for myself based on the miles I cycled and the time it took. The app seems more accurate. Has anyone else had this problem as both the computer and app are recording a similar distance and time but the computer seem to by way out with the average speed.

(last ride was 34.7miles and took 2 hours 20 minutes. Which I calculate to be an average speed off 24.78mph)

Maybe my calculations are incorrect

jameses

Ally83 wrote:

(last ride was 34.7miles and took 2 hours 20 minutes. Which I calculate to be an average speed off 24.78mph)

Maybe my calculations are incorrect

I make that about 15mph.

Rigged

14.87 mph

http://www.machinehead-software.co.uk/b ... _calc.html

jim453

Speed is distance divided by time taken. You may need to be careful how you express the time in the calculation because 2 hours 30 mins is 2.5 hours not 2.3 hours for instance.

Just trying to understand how you could have messed up the calculation.

wheezee

I get 17.56mph.

dabber

It's 14.87 mph as posted previously.

The manual calculation is....
34.7 miles divided by the number of minutes taken, in this case 140 minutes.
This gives you a distance of 0.24785714285714285714285714285714 miles travelled for each minute of the ride.
To give an average miles per hour you multiply by 60.

60 times 0.24785714285714285714285714285714 = 14.87

rpd_steve

This is just silly. :P 2 hours 20 mins is 2.333 hours.

s=d/t
s=34.7/2.333
s=14.87 miles per hour :idea:

The comp is right, the app is wrong. Often GPS can be patchy of phones. The Polar should alow you to see your GPS accuracy - typicly about 24 ft on my Garmin 800, so it knows where I am +- 8m. So on an 8m ride it may get my speed out by 100% but on a 50 km ride it is accurate to 0.016% of exact.

And with the greatest respect a 24mph average would have been very impressive over 35 miles, particulally if you are solo, which I assume you are as otherwise you would have asked a fellow ride their average. If you was capable of 24 mph you would dam well know it! 8)

Ally83

Thanks guy realised I was converting the time into minutes and the app is giving the wrong units.

Feel like an idiot now lol

t5nel

Was the app reading in km/h?

15mph ~ 24km/h

team47b

Now, if you had a bike computer that said you were averaging 24mph when doing 15mph you could make a few bob selling that on this forum.

Yeah I realise there are a few people with these already

This is intended to be humuorous and any similarity with real people is purely co-incidental keep your toys in the pram